Overall there is not a hairsbreadth difference between them. Hayek saw this in the 30s and 40s:
Although our modern socialists’ promise of greater freedom is genuine and sincere, in recent years observer after observer has been impressed by the unforeseen consequences of socialism, the extraordinary similarity in many respects of the conditions under “communism” and “fascism.” As the writer Peter Drucker expressed it in 1939, “the complete collapse of the belief in the attainability of freedom and equality through Marxism has forced Russia to travel the same road toward a totalitarian society of un-freedom and inequality which Germany has been following. Not that communism and fascism are essentially the same. Fascism is the stage reached after communism has proved an illusion, and it has proved as much an illusion in Russia as in pre-Hitler Germany.”
No less significant is the intellectual outlook of the rank and file in the communist and fascist movements in Germany before 1933. The relative ease with which a young communist could be converted into a Nazi or vice versa was well known, best of all to the propagandists of the two parties. The communists and Nazis clashed more frequently with each other than with other parties simply because they competed for the same type of mind and reserved for each other the hatred of the heretic. Their practice showed how closely they are related. To both, the real enemy, the man with whom they had nothing in common, was the liberal of the old type. While to the Nazi the communist and to the communist the Nazi, and to both the socialist, are potential recruits made of the right timber, they both know that there can be no compromise between them and those who really believe in individual freedom.
— F.A. Hayek, The Road to Serfdom
The Left does not believe in individual freedom, they are consistent there.
Hayek is 100% correct in as much as how those who want big government all look the same to people like us who want small government and to us, watching socialists and fascists squabbling over "
which form of big government is superior" just seems like clown to clown communication
To them though, those who believe in a dictatorship, the nationalists on the right and the internationalists on the left couldn't look more different. Reagan talked about this generally in A Time For Choosing.
https://www.reaganlibrary.gov/reagans/ronald-reagan/time-choosing-speech-october-27-1964
"You and I are told increasingly we have to choose between a left or right. Well I'd like to suggest there is no such thing as a left or right. There's only an up or down - [up] man's old-aged dream, the ultimate in individual freedom consistent with law and order, or down to the ant heap of totalitarianism."
Those down in the ant heap of totalitarianism squabble over whether they are left wing or right wing ants.(according to Reagan)
Personally, I think an up/down political scale as Reagan uses makes way more rational sense than a left/right political scale. Up, as in vertically, not on a plotted scale like so many stupid square charts. Up is small government. Down is big government, and that is all.